I'm really close to pulling the trigger on the GA5166X for my E53 with nav and no dsp. I really just have one question that I haven't seen addressed. I made a post in the mobile electronics area, but have got no replies.

Can you play a DVD and have the video routed to rear, headrest mounted monitors and continue to use navigation, music, etc. on the main screen? I see that the feature is listed on the previous windows iteration. The D5166X but I don't see that on here.
This is a feature I NEED to have. We do road trips fairly regularly and recently bought and returned a 2 screen headrest DVD player for the kids. It sucked having to be driving and have my wife climb over the seat to get the DVD in, press play on the menu to start the thing, etc. It isn't safe and it was a major PITA. I need to be able to do that from the head unit, but still be able to have my music playing off of bluetooth or USB and my navigation up at the same time the DVD is going in the back.

EDIT: Finally got an email back from Eonon. It does not allow music playback at the same time you have DVD playback in the rear screens. It allows nav, but no music. Any other head units to look at that are similar, but will allow this?